In a conventional diesel-electric locomotive, drive traction motors provide the motive force to move the train. Typically, a diesel engine drives an alternator, which supplies current to drive traction motors, which, in turn, propel the locomotive forward or backward. When propelled as such, a locomotive is said to be motoring.
The traction motors, however, perform an additional function. Once the locomotive is in motion, traction motors may be configured to generate electricity instead of consuming it. As generators, the traction motors convert the locomotive's kinetic energy into electrical energy, thereby slowing the locomotive. Using the traction motors to reduce speed is called dynamic braking. Because there is no suitable storage medium for the generated electrical energy, an electrically resistive grid is used to convert the electrical energy into heat energy, which is vented to the atmosphere through a resistive grid exhaust on one side of the locomotive. The resistance grid exhaust is adjacent to an operator cabin and a walkway used by the operator during regular maintenance when the locomotive is stationary.
While the locomotive is stationary, during a self-load mode, the resistive grid may be used to test load a locomotive's power alternator and diesel engine. The resistive grid is disconnected from the traction motors and connected to the locomotive's alternator, and continues to convert electrical energy to heat energy, which is vented out through the resistive grid exhaust, as in the dynamic braking mode. When the locomotive is stationary, such as in the self-load mode, the operator may walk on the walkway to perform regular maintenance, and thus be positioned in the vicinity of the resistive grid exhaust. Accordingly, there is a need to provide additional safety in the walkway area to address these circumstances.